Field
Exemplary embodiments of the invention relate generally to a method of maintaining a tilt angle, a method of controlling tilting, and a surveillance camera, and more specifically, to a method of maintaining a tilt-angle and a method of controlling tilting of a surveillance camera capable of performing a tilting operation by using an open loop control method.
Discussion of the Background
When controlling a tilting operation of a surveillance camera, an open loop control method or a closed loop control method may be used.
In a closed loop control method, returning is controlled by an encoder, etc., to detect and correct an out-of-phase state of tilting. However, when the tilting is performed by employing the closed loop control method, an expensive location detecting device such as an encoder has to be used, thereby increasing manufacturing costs of the surveillance camera.
Accordingly, most surveillance cameras adopt an open loop control method while using a stepping motor. However, when the open loop control method is used as described above, the surveillance camera may not instantly detect and correct for variation in a tilt-angle due to gravity, vibrations, wind, heat, etc. as time passes after finishing the tilting operation. In this case, a region that is not desired by a user is monitored for a while, and thus, a gap in surveillance occurs.
The above information disclosed in this Background section is only for understanding of the background of the inventive concepts, and, therefore, it may contain information that does not constitute prior art.